1. Field of the Invention
The present invention relates to a resin-molded semiconductor device.
2. Description of the Related Art
Conventionally, when a wiring part (e.g., lead frame) is electrically coupled with a circuit wiring formed on a circuit board (e.g., semiconductor substrate) and the wiring part and the circuit board are sealed with a molded resin, a stress may be generated at an interface between the circuit board and the molded resin and/or between mounted parts disposed on the circuit board and the molded resin due to curing of the molded resin. In addition, a thermal stress may be generated at the interfaces when a product including the circuit board is in use. The stresses may cause various problems including a cracking of a protective coating glass disposed on the circuit board and detachments of the interfaces. Furthermore, a disconnecting of a bonding part, a breaking of the mounted parts, and/or a breaking of a joining agent (e.g., solder) for attaching the mounted parts to the circuit board may occur due to the detachments of the interfaces.
When resin is molded after a protective coating glass is coated on the mounted parts disposed on the circuit board and a release agent is applied to an outer surface of the protective coating glass or when a protective coating glass that has a small bonding strength to the molded resin is used, a detachment occurs at an interface between the protective coating glass and the molded resin. Thereby, the stress is not applied to the protective coating glass and the protective coating glass can be prevented from cracking.
In the above-described cases, a portion at which a bonding strength to the molded resin is high, e.g., an end portion of the circuit board, is prone to receive the stress. Thus, a detachment may occur between the end portion of the circuit board and the molded resin. Furthermore, a disconnecting of the bonding part and a breaking of the mounted parts may occur after the detachment progresses.
Alternatively, JP-1-261850A discloses a semiconductor device in which the protective coating glass is coated on the mounted parts disposed on the circuit board, a flexible part that has a low Young's modulus (e.g., silicone resin) is applied to an outside of the protective coating glass, and then resin is molded. Because silicone resin, which is disposed between the protective coating glass and the molded resin, is deformable, the stress is difficult to transfer from the molded resin to the protective coating glass. Thus, the protective coating glass can be prevented from cracking.
However, in this case, solder may crack due to a difference in rates of thermal expansion of the mounted parts and the circuit board depending on a temperature, a size of the circuit board, and a size of the electronic element. Thus, a disconnecting of the bonding part and a breaking of the mounted parts may occur.